This invention relates to joints between fibre-optic communication cables and in particular to methods of, and ferrules for use in, making such joints.
Fibre-optic communications cables generally include some form of strength member to carry the strain involved in installing the cables in ducts or laying them underwater, since the fibres are not capable of bearing such strains themselves. When two fibre-optic cables are jointed there must, therefore, be means provided at the joint to transfer the strain from one cable strength member to the other cable strength member.
In the case of fibre-optic cables which are used for submarine purposes, it is necessary that the cable also includes metallic conductors for use in supplying electrical power to regenerators, which must be employed when the optical fibres are used for relatively long distances. When jointing such cables means must also be provided for jointing the metallic conductors. One such form of cable joint is disclosed in our co-pending U.S. application Ser. No. 965,678 (Parfree) in which individually clad optical fibres are arranged in an aluminum tube which acts as a protection against the effect of pressure. The split in the tube can be sealed by soldering or welding, thereby forming a pressure-resisting protective tube around the optical fibres. The tube is surrounded by a cylindrical strength member formed for example by one or more layers of high tensile steel wires or synthetic fibres, and this member is surrounded by a layer of copper tape which acts as a conductor for the supply of power to the regenerator, which is in turn surrounded by a layer of dielectric, for example polyethylene.